The present invention relates to a method for cordlessly connecting data terminal equipment to a data transmission network via the DECT telecommunications system.
It is a known method to connect data terminal equipment to a public fixed telephone network via a modem. Then the interface between the data terminal equipment and the modem complies with the CCITT standard V.24, for example. However, there is in sight a growing need to transmit data between mobile data terminal equipment and a data transmission network, which requires a cordless interface.
Wireless mobile telephone systems, like the NMT and GSM, are used mainly to transmit speech. These systems are long range telecommunications networks. In addition to the speech connection, these networks also provide methods for the transmission of digital data and for wireless connection of data terminal equipment to a telecommunications network.
The above systems operate in a wide area and, because of the long range, the number of radio channels available is very limited. Since a modem connection usually uses a lot of connection time, it is unreasonably expensive to reserve a radio channel for that purpose. On the other hand, inside a building the operating range is short.
There are wireless modems and cordless LANs for the transmission of data inside buildings. However, these systems have high equipment costs and they are in-compatible with other systems using wireless data transmission. There are also cordless telephone systems and paging systems for the transmission of data inside buildings but a wireless connection of data terminal equipment to these systems is not possible.
For local wireless communication there is the digital European cordless telecommunications (DECT) system which provides advantageous data transmission means for the implementation of calls or paging. A disadvantage of the system is, however, that it does not allow the connection of data terminal equipment/modem.
It is an object of the present invention to provide a method and system for connecting data terminal equipment to a fixed communication network via the cordless DECT system. The method of the invention is characterized in that, in the transmitting radio part (PP, FP), the information transmitted between the portable (PP) and fixed (FP) radio parts is inserted wholly or partly in frames of a protocol complying, in whole or in part, with the DECT standard and, in the receiving radio part (FP, PP), the information is read from said frames.